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一、方法要点: 试样用盐酸加双氧水溶解,加氨水使Cu、Zn分别形成氨络合物,Sn为偏锡酸沉淀,Pb生成硷式碳酸铅沉淀过滤分离。在醋酸、醋酸铵缓冲溶液中(PH≈5—6),用二甲酚橙作指示剂,用EDTA滴定Zn、Cu含量,用硫脲掩蔽Cu测定Zn。在六次甲基四胺溶液中,用草酸掩蔽Fe,用EDTA滴定Pb。用氟化铵析出法测定Sn。
First, the method points: The sample was dissolved in hydrochloric acid and hydrogen peroxide, ammonia and ammonia to make Cu, Zn, respectively, form ammonia complex, Sn is a stannous acid precipitation, Pb generated by alkaline lead carbonate precipitation separation. In acetic acid, ammonium acetate buffer solution (pH≈5-6), with xylenol orange as indicator, titration with EDTA Zn, Cu content, with thiourea to mask the Cu determination of Zn. In hexamethylenetetramine solution, Fe was weeded with oxalic acid and Pb was titrated with EDTA. Determination of Sn by ammonium fluoride precipitation method.